This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to patent application Ser. No. 0100652-7 filed in Sweden on Feb. 27, 2001, the entire content of which is hereby incorporated by reference.
The present invention relates to a method for chip removing machining, wherein a so-called high pressure cooling is applied. At least one jet of cooling liquid under high pressure is directed towards the contact area between a cutting edge of a cutting insert for chip removing machining and the workpiece that the cutting insert machines. The invention also relates to a cutting tool for chip removing machining.
A cutting tool where one or more jets of cooling liquid under high pressure is sprayed in the area between the chip and the chip surface of the cutting insert is previously known from, for instance, Swedish Patent No. 513 480. This type of cooling/chip control henceforth will be denominated as xe2x80x9cover-cooling,xe2x80x9d because the jet is directed downwardly toward the cutting insert from above. The fact is that a jet of cooling liquid under high pressure according to Swedish Patent 513 480 not only provides cooling but also a certain degree of chip control.
Certain types of materials are of the nature that the chips cannot be broken by means of the geometry of the cutting insert. For this reason, the chips leave the cutting edge in the form of long, tangled chips, which may cause interruptions in the machining process as well as also destroy the components being machined. An additional disadvantage is the subsequent chip handling, especially disposal of unwieldy chip tangles, which may mean a risk of injury for the operator.
By supplying one or more jets of cooling liquid under high pressure in the zone between the chip and the chip surface of the cutting insert, a safe and reliable chip control can be obtained. The prerequisite for obtaining such a chip control is, however, that certain characteristics of the jet, i.e., flow, pressure (velocity) and point(s) of impact should be well adapted in relation to the current cutting criteria, i.e., cutting depth, feeding, cutting speed and material properties (hardness, strength and machinability). However, in this connection, it should be pointed out that the jet characteristics which provide an optimum chip control do not always ensure an optimum temperature control/cooling of the chip removing machining.
Among those skilled in the art, different opinions are found as to what is to be regarded as xe2x80x9clowxe2x80x9d and xe2x80x9chighxe2x80x9d fluid pressure, respectively. However, generally the classification should be made in the following intervals:
Low pressure less than 10 bar
Intermediate pressure 10-100 bar
High pressure greater than 100 bar
A primary aim of the present invention is to provide a method and a device of the kind mentioned in the introduction where a satisfactory chip control is provided at the same time as a satisfactory temperature control/cooling is provided. Thereby, an increased, but above all a more predictable, service life of the cutting insert is obtained.
Yet another aim of the present invention is to obtain an improved surface profile on the machined workpiece in comparison to conventional cooling.
One aspect of the invention relates to a method for the chip removing machining of a workpiece. The method utilizes a cutting tool which comprises a cutting insert, an over-cooling nozzle arranged for directing a jet of cooling liquid downwardly toward a contact area between the workpiece and a chip surface of the cutting insert, and a sub-cooling nozzle arranged for directing a jet of cooling liquid upwardly toward a contact area between the workpiece and a flank surface of the cutting insert.
The method comprises the steps of:
A) effecting relative movement between the workpiece and the cutting insert for cutting chips from the workpiece, and
B) emitting, during step A, a jet of cooling liquid from at least the sub-cooling nozzle toward the second contact area.
The method can also be practiced by simultaneously emitting jets of cooling liquid from the over-cooling nozzle and the sub-cooling nozzle.
Another aspect of the invention pertains to a cutting tool for the chip removing machining of a workpiece. The tool comprises a seat for a cutting insert, an over-cooling nozzle, and a sub-cooling nozzle. The over-cooling nozzle is arranged for directing a jet of cooling liquid downwardly toward the seat (and thus toward a chip surface of a cutting insert). The sub-cooling nozzle is arranged for directing a jet of cooling liquid upwardly toward the seat (and thus toward a flank surface of a cutting insert).